The present invention relates to a transmission and/or reception unit (“transceiver”) in particular for transmitting and/or receiving DSL (digital subscriber line) data.
So-called DSL linecards, that is, transmission/reception devices, of a central office (CO) for DSL communication have different so-called granularities, that is, numbers of supported channels. Granularities of 8, 24, 32, 48, 64, or 96 are customary. Individual DSL chip sets have either 12 channels or 16 channels; the usual granularity of 48 therefore has to be divided into 48 (4×12) and 48 (3×16) depending on the DSL chip set on which the linecard in question is based.
In particular, there are ASICs (application-specific integrated circuits) for the processing of data received by a DSL transceiver, or data to be transmitted, which support precisely 12 channels on an interface for this DSL transceiver. The interface used is then customarily a UTOPIA interface according to the ATM Forum standard (ATM=asynchronous transfer mode).
FIG. 3 schematically illustrates such a chip set or DSL transceiver 11. A transceiver module 12 transmits or receives data signals over a transmission line 15 and delivers them at the back, that is, for processing, via an interface 13, for example a UTOPIA interface. A data line 14, which has 12 channels or 16 channels depending on the chip set being used, can be connected to this interface 13.
Owing to the situation described above, each manufacturer with a corresponding DSL chip set can address only some of the aforementioned granularities without overhead, that is, without unused channels. With 12-channel chip sets, it is possible to produce granularities of 24, 48 (4×12), 72 and 96 without overhead, and granularities of 32, 48 (3×16), 64 and 96 with a 16-channel chip set.
Conventionally, non-matching granularities are produced by implementing the next-highest possible channel number on the linecard and simply not using the unneeded channels. In order to build a 64-channel linecard with a 12-channel chip set, for example, the linecard is configured for 72 channels which gives an overhead of eight unused channels.
Overall, there is a great need for the granularities which can be produced by means of a 16-channel chip set. When using the aforementioned 12-channel ASICs, however, the problem arises that a 48-channel linecard cannot be built simply from three 16-channel chip sets or transceivers, since only 12 channels of an interface of the DSL transceiver in question can be used by each ASIC. A manufacturer of a 16-channel chip set must therefore use four transceivers to build such a 48-channel linecard, but with only 48 out of the theoretically available 64 channels then being used, that is to say there is an overhead of 16 channels whose production entails costs but which are not needed.
A transmission and/or reception unit in which the available channels can be used more flexibly is needed.